Receiver circuit

Abstract

A first phase adjustment circuit adjusts phases of a data decision clock signal and a first boundary decision clock signal according to a phase adjustment amount based on an output signal of a data decision circuit and an output signal of a first boundary decision circuit. A second phase adjustment circuit adjusts a phase of a second boundary decision clock signal according to a result of adding the phase adjustment amount and a phase adjustment amount offset. An adaptive equalization control circuit adjusts an equalization coefficient of an equalization circuit according to a data width of an output signal of the equalization circuit based on a logical comparison result between the output signal of the data decision circuit and an output signal of a second boundary decision circuit when the phase adjustment amount offset is changed.

What is claimed is: 
     
       1. A receiver circuit, comprising:
 an equalization circuit equalizing an input signal; 
 a first data decision circuit making a decision on an output signal of the equalization circuit in synchronization with a first data decision clock signal, and a second data decision circuit making a decision on the output signal of the equalization circuit in synchronization with a second data decision clock signal, the first data decision clock signal and the second data decision clock signal each having different phase and being able to adjust a phase independently of each other; 
 a first boundary decision circuit making a decision on the output signal of the equalization circuit based on a first boundary decision clock signal, and a second boundary decision circuit making a decision on the output signal of the equalization circuit based on a second boundary decision clock signal, the first boundary decision clock signal and the second boundary decision clock signal each having different phase and being able to adjust a phase independently of each other; 
 a selection circuit dynamically switching between a selection side and a non-selection side with respect to the first and second boundary decision circuits; 
 a phase adjustment circuit adjusting phases of the first and second data decision clock signals and the selection side of the first and second boundary decision clock signals according to a phase adjustment amount based on output signals of the first and second data decision circuits and the selection side of output signals of the first and second boundary decision circuits, and adjusting a phase of the non-selection side of the first and second boundary decision clock signals according to a result of adding the phase adjustment amount and a phase adjustment amount offset; and 
 an adaptive equalization control circuit adjusting an equalization coefficient of the equalization circuit according to a data width of the output signal of the equalization circuit based on a logical comparison result between the output signals of the first and second data decision circuits and the non-selection side of the output signals of the first and second boundary decision circuits when the phase adjustment amount offset is changed. 
 
     
     
       2. The receiver circuit according to  claim 1 , wherein
 a timing of switching between the selection side and the non-selection side in the selection circuit is adjustable. 
 
     
     
       3. A receiver circuit, comprising:
 an equalization circuit equalizing an input signal; 
 a first data decision circuit making a decision on an output signal of the equalization circuit in synchronization with a first data decision clock signal, and a second data decision circuit making a decision on the output signal of the equalization circuit in synchronization with a second data decision clock signal; 
 a first boundary decision circuit making a decision on the output signal of the equalization circuit based on a first boundary decision clock signal, and a second boundary decision circuit making a decision on the output signal of the equalization circuit based on a second boundary decision clock signal; 
 a selection circuit dynamically switching between a selection side and a non-selection side with respect to the first and second boundary decision circuits; 
 a phase adjustment circuit adjusting phases of the first and second data decision clock signals and the selection side of the first and second boundary decision clock signals according to a phase adjustment amount based on output signals of the first and second data decision circuits and the selection side of output signals of the first and second boundary decision circuits, and adjusting a phase of the non-selection side of the first and second boundary decision clock signals according to a result of adding the phase adjustment amount and a phase adjustment amount offset; and 
 an adaptive equalization control circuit adjusting an equalization coefficient of the equalization circuit according to a data width of the output signal of the equalization circuit based on a logical comparison result between the output signals of the first and second data decision circuits and the non-selection side of the output signals of the first and second boundary decision circuits when the phase adjustment amount offset is changed, wherein 
 the adaptive equalization control circuit performs, for every set value of the equalization coefficient, a logical comparison between the output signals of the first and second data decision circuits and the non-selection side of the output signals of the first and second boundary decision circuits a given number of times with respect to each of set values of the phase adjustment amount offset, and obtains an absolute value of a cumulative addition value of logical comparison results; and 
 the adaptive equalization control circuit decides that a set value of the equalization coefficient which maximizes an integral value, obtained by integrating the absolute value of the cumulative addition value with respect to a set range of the phase adjustment amount offset, is an optimal value. 
 
     
     
       4. The receiver circuit according to  claim 3 , wherein a set range of the phase adjustment amount offset is adjustable. 
     
     
       5. The receiver circuit according to  claim 3 , wherein the given number of times is adjustable. 
     
     
       6. A receiver circuit, comprising:
 an equalization circuit equalizing an input signal; 
 a first data decision circuit making a decision on an output signal of the equalization circuit in synchronization with a first data decision clock signal, and a second data decision circuit making a decision on the output signal of the equalization circuit in synchronization with a second data decision clock signal; 
 a first boundary decision circuit making a decision on the output signal of the equalization circuit based on a first boundary decision clock signal, and a second boundary decision circuit making a decision on the output signal of the equalization circuit based on a second boundary decision clock signal; 
 a selection circuit dynamically switching between a selection side and a non-selection side with respect to the first and second boundary decision circuits; 
 a phase adjustment circuit adjusting phases of the first and second data decision clock signals and the selection side of the first and second boundary decision clock signals according to a phase adjustment amount based on output signals of the first and second data decision circuits and the selection side of output signals of the first and second boundary decision circuits, and adjusting a phase of the non-selection side of the first and second boundary decision clock signals according to a result of adding the phase adjustment amount and a phase adjustment amount offset; and 
 an adaptive equalization control circuit adjusting an equalization coefficient of the equalization circuit according to a data width of the output signal of the equalization circuit based on a logical comparison result between the output signals of the first and second data decision circuits and the non-selection side of the output signals of the first and second boundary decision circuits when the phase adjustment amount offset is changed, wherein 
 the adaptive equalization control circuit performs, for every set value of the equalization coefficient, a logical comparison between the output signals of the first and second data decision circuits and the non-selection side of the output signals of the first and second boundary decision circuits a given number of times with respect to each of set values of the phase adjustment amount offset, and obtains an absolute value of a cumulative addition value of logical comparison results; and 
 the adaptive equalization control circuit decides that a set value of the equalization coefficient which minimizes a range of the phase adjustment amount offset, in which the absolute value of the cumulative addition value does not match the given number of times, is an optimal value. 
 
     
     
       7. The receiver circuit according to  claim 6 , wherein a set range of the phase adjustment amount offset is adjustable. 
     
     
       8. The receiver circuit according to  claim 6 , wherein the given number of times is adjustable.